Bank Error Denied, Sent Acct. to RJM

These people have had this in their desks for quite awhile; I have told them repeatedly that M&T bank is trying to collect on a legitimate bank error, i.e. they seized a SOCIAL SECURITY FEDICARY ACCT!!! That is against the law!!! I know this because I have worked both as a telephone banker AND a collection agent. The quote unquote, "Non-refundable bank fee" for an ILLLEGAL garnish, SHOULD have been refunded because the BANK broke the law!! The subsequent fees were assessed because of the bounced checks that occurred because of the illegal seizure of funds!! How do I fight this one? I have told them time and time again, I refuse to pay for a BANK ERROR!! They, on the other hand, have got the corporate view of "might is right."